1. Field of the Invention
This invention encompasses lubricating compositions for use in automatic transmission fluids, tractor hydraulic fluids, manual transmission fluids, continuously variable transmission fluids, wet brake and wet clutch fluids, hydraulic fluids and the like. The fluids encompass both lubricating and functional properties. The compositions embody sulfur and boron-containing components as well as antifoam agents in an oil of lubricating viscosity. The compositions reduce wear in the device in which they are used. Decreased air entrainment in the fluid results in reduced fluid compressibility which results in improved operational parameters of devices containing the fluids.
2. Related Art
Functional/lubricating fluids are well known. As manufacturers of devices containing these fluids change equipment designs and operational specifications for these devices, such as automatic transmissions, new lubricating formulations must be developed. Such new formulations result in lubricating compositions with improved operational standards.
U.S. Pat. No. 5,422,023 describes lubricant compositions alkyl substituted dimercaptothiodiazoles together with an alpha-olefin/malic ester copolymer in a lubricating oil.
U.S. Pat. No. 4,990,273 describes an antiwear additive for lubricating compositions which is the reaction product of 2,5-dimercapto-1,3,4-thiadiazole with an aldehyde and an amine.
U.S. Pat. No. 4,612,129 describes dimercapto-thiadiazole derivatives as corrosion inhibitors used in compositions containing a metal salt of a dithiocarbamic acid of formula R.sub.1 (R.sub.2)N--CSSH and an oil soluble sulfurized organic compound.
U.S. Pat. No. 4,301,019 describes reacting mercapto-thiadiazole with hydroxyl-containing unsaturated esters, or their borated derivatives to yield products useful as friction reducing additives in lubricants.
U.S. Pat. No. 4,140,643 describes reacting an oil-soluble dispersant with a dimercapto-thiadiazole and subsequently reacting the intermediate thus formed with a carboxylic acid or anhydride. The compositions are useful dispersants, extreme pressure agents and inhibitors of copper activity.
U.S. Pat. No. 4,136,043 describes reacting an oil soluble dispersant and a dimercapto-thiadiazole at 100-250.degree. C. until the reaction product will form a homogeneous blend with a lubricating oil.
European Patent Application publication number 0630 960 A1 discloses the use of dimercapto-thiadiazoles with a copolymer of methacrylate, methyl-methacrylate and an amine-based antioxidant.
European Patent Application publication number 0601266 A1 describes novel compounds prepared by reacting 2,5-dimercapto-1,3,4-thiadiazole, aldehydes, and aromatic amines and their use as antiwear and antioxidant agents in lubricating compositions.